TITLE: Multi-level associations between medical marijuana laws and substance use disorder treatment Medical marijuana laws (MMLs) have been increasingly adopted throughout the United States; more than half of people live in states that permit medical use of marijuana. While MMLs have been associated with treatment admissions for substance use disorders (SUDs), the relationship between MML and SUD treatment is complex and dynamic and can vary based on specific MML provisions. Marijuana dispensaries, for example, have been associated with increases in marijuana treatment and decreases in opioid treatment admissions. However, there are critical gaps in the literature regarding the mechanisms through which MMLs can affect SUD treatment use and related outcomes. The proposed research takes a multidisciplinary approach to understand and isolate the effects of MML on SUD treatment across gender and racial/ethnic groups, accounting for individual- (e.g., perceptions), community- (e.g., criminal justice), and state-level (e.g., Medicaid expansion) factors. Estimating the effect of structural factors such as MMLs on SUD treatment use could have significant public health impact, as SUDs are associated with a variety of negative health consequences, and the majority of people who meet SUD criteria do not receive SUD treatment. MML effects on individual SUD treatment need and perceptions will be estimated using data from the restricted use National Survey on Drug Use and Health from 2004 onwards. MML effects on criminal justice referrals to SUD treatment will be estimated using the 1992-2014 Treatment Episodes Data Set. The effects of MMLs on health outcomes and service costs between 2004 and 2014 will be assessed in a cohort of adults with Medicare/Medicaid. Interactions between gender and race/ethnicity will be tested in order to determine whether MMLs are contributing to changes in health care disparities. The research in this K01 proposal supports the National Institute on Drug Abuse objective to ?assess the impact of federal, state-, and systems-level policies related to drug use and substance use disorders on public health and well-being.? Three specific training areas will be incorporated to carry out the research aims, including: (a) structural contributors to health care disparities in SUD treatment; (b) dynamics between criminal justice, health policy, and treatment systems; and (c) health financing and health economics analysis. The ambitious training and research aims are feasible in the 5-year K01 award with the support of the interdisciplinary mentorship team at Columbia University (Drs. Martins, Metsch, Hasin, and Muennig) and collaborators (Dr. Fagan, Crystal and Alexandre), culminating in the development of an R01. The career development plan will support the applicant?s goals and trajectory towards research independence.